95 chevy 6.5 keeps shutting off!
 

i have a 95 chevy 3500 6.5 4x4 and it will just die like you turned the key off, has a new pmd and cooler which is located on the front bumper now. it seems to only do it when it warms up. yesterday i drove it all day without it giving me one problem, and today i drove it and it started to jerk back and forth while driving like it was starving for fuel, than the check engine light went out and it goes back to normal. someday's itll do it some days it won't. i put all new engine grounds on it today thinking that was it but it wasn't. i can't find a obd-1 scanner so i used the key. and i believe this is the codes it showed after clearing the codes and driving a day. 1st was 61. than 71. than 83 than 62 than 63 than 81. i cannot find out what these codes are for. any help would be great!! :tu:

DTC 61 - Turbo Boost Sensor Circuit High
DTC 71 - Set/Coast Switch Fault (Cruise Control)
DTC 83 - Torque Converter Clutch


DTC 62 - Turbo Boost Sensor Circuit Low
DTC 63 - Accelerator Pedal Position 3 Circuit High
DTC 81 - Transmission 2-3 Shift Solenoid Circuit


Sure seems like a ground issue for the ECM.
Check the ground cluster at the rear passenger side of the intake manifold,should be (IIRC) 3 ground wires with clean secure connections.

okay, i'll try that but if that doesn't work what else could it be?:humm:

Bad ECM or bad wiring?

Mice like to camp out under the intake and around the harnesses if it has sat for a while.

could a ignition problem cause this?

Sure could,typically the dash/instrument cluster will go dark but the radio and/or blower motor will keep working when the ignition switch is at fault.
In my experience it does not throw codes when the switch is the problem-just stalling.

okay, i will check all the wiring and check ecm grounds and i will get back to you whenever i figure something out on this thing. i'm thinking it might be ignition, cause today i drove it for 30 minutes and it drove perfect, plenty of power no jerking or shutting off. i stopped and shut it off for maybe 10 minutes, got back in fired it up and drove it maybe 2 miles and it jerked like crazy than eventually shut off. :scare2: than i got to where i was going, let it sit for 2 hours and it drove it to the fuel station with a few jerking problems. put fuel in it and it drove perfect the enitre 30 minutes from to home. does this sound like ignition problem? i've noticed it doesn't do it as much if it has plenty of fuel in the tank. than starts when i get low. so idk! :argh: lol

If the problem happens with a low fuel level it might mean that you have a hole in the sending unit pickup tube in the fuel tank that lets it suck air when it is no longer covered by fuel?
How does it restart after a stall,kind of difficult?

Do you get a lot of suction when you take the fuel filler cap off?
A plugged fuel cap vent might be a problem also?

When it happens, try jiggling the switch to see if it clears. But I agree with the above post. Maybe need a new sender.

Yeah it's kind of difficult to get started again, normally about 5-7 seconds of cranking than it finally hits. Would it sucking air cause it to lose power? Cause when it loses it's power I can have it to the floor and it won't go over 50mph in 5th gear. I can pull over shut it off and 5 seconds later fire it up and have full power again. But when it shuts off it's like turning the key off than takes quite a bit of cranking to get it started. Done it today in the bank drive thru:td:

Sounds like 2 possible problems,a bad oil pressure switch and sucking air somewhere in the fuel supply side.

The oil pressure switch supplies power to the lift pump whe the engine is running and even though the gauge woks can still be bad.

Replace with AC Delco ONLY,and google OPS relay mod.

i checked every single wire on and below the motor and found nothing. everything looked to be in good shape. i put a new fuel filter on it. on the bottom of the fuel filter like the housing of it, there's like a plastic screw on lid. just above the 3 fuel lines that hooks in it, it seems to be leaking right there and was wondering if there's suppose to be a oring there. i think it must be a wire or something cause on the way home tonight it was jerking and what not like it always does, and the voltage drops quite a bit when it does it. like it'll be on say 14, and when the check engine light come's on and it starts jerking back and forth the voltage drops to like 12 or so. i'm really at a lost on this truck. it's driving me nuts! lol

The bottom of the filter housing holds the fuel heater,and yes it is a common leak place-new O-ring required.
While you have it out change the water in fuel sensor O-ring too and do not try and re-use the new fuel filter-they are not intended tio be taken on/off repeatedly and the O-ring tends to stretch and no longer seal.
'
Dropping voltage is an odd occurrence.

okay, i checked the ecm behind the glovebox and all the wires look good except the black ground wire that hooks to the ecm plugins the ground wire goes down and bolts into the side of the glovebox it looks like the previous owner messed with it and there's no butt connectors on it it's just twisted together. everytime i reset and check the check engine light codes their always different. could this ground problem cause all the trouble i'm having?

If its not a very good connection, then yes. I think the voltage drop may be part of this problem. Does this problem happen when you hit a bump?

BTW, Very good investigation work. Sounds like youre on the track to fixing it.

The voltage drop happens at random, its kind of weird. Because I shook all ECM wires and ground wires to the ECM while it was running and it seem to have no effect so I'm still not totally sure that is the problem. It's driving me crazy I've been searching and checking out every single wire. The break light wires seem to have a short cause they don't work but if you hit a bump they come on. Could it be possible that the short in the break lights that it could draw enough juice to where the lift pump or injection pump won't work correctly?

Grounds are the single biggest item to have clean and secure on these trucks,refer back to post #2 of this thread.
An bad ECM ground will sure cause your code troubles.

The brake lights should blow a fuse if there is a dead short.

no it doesn't do it when i hit a bump, it's just random like i could be cruising at 60 on a smooth road and it'll randomly drop. the break lights come on and off when you hit a bump also. i don't know if maybe it's drawing enough juice to where the lift pump or injection pump won't work right. i'm considering all possible ways lol.

Brake lights coming on after a bump likely means the brake switch needs to be adjusted.

injection pump $1800 happened to me

Injection pumps do go,but more often than not the PMD is the main problem with IP's,unless you are having hot start issues and you find that the truck starts better when you pour water over the hot IP.

im having the exact same problems. Did you ever get it straightened out?

Yes please keep us posted I am having similiar problems with my 98. I have a remote pmd behind the grill and I thought maybe it went bad, so I got a heath pmd and mounted underneith. Now when my truck stalls most of the time if I switch to the other pmd it will fire right back up and away I go. Other times I will be sitting on the side of the road swearing away till it starts. I cleaned my grounds on the passenger side of the motor and no change. Next I am going to check ecm ground.

If the gauges die at the time of the stall suspect the ignition switch.

Is there any way to check the ignition switch, or should I just replace it so I know wether or not its the problem.

Most common problem is that the gauges die during a stall but radio and blower motor keep working-that points straight at the ignition switch.

When I had a 6.5 in my 92 that happen to me like you I went through every wire and my dad finally found split head light wires, we ran all new wires to everything, and after that the pickup didn't quit unless I wanted it too.

I changed ignitio drove to town (30 miles) and on way home stalled but started right back up. Drove to work (42 miles) on way home stalled wouldnt fire until I switched pmd's. I have 2 remote pmd's one behind the grill and a Heath one underneith. After switching it fired right up and I was on my way:scare2:

---AutoMerged DoublePost---

I cleaned the grounds on the motor and I checked the ecm grounds behind the glovebox and they looked good. I am not sure about the ops mod since mine is a 1998 I read that it was for the 96 and older. What should I look at next?

Checked every ground that i could see wiggled every wire i could reach, and when i shook the harness' on the ecm one wasn't securely plugged in and it came unplugged and died. Going to drive it again tomorrow with my fingers crossed and hopefully no more stalling.

Still Stalling out. I went to town the other day, and the truck stalled, the tach read 2000 rpms for about 10 seconds but i had no power then dropped off to 0 and it was dead. Cranked it over and it fired right back up. I had heard of the ops possibly being an issue so I had that unplugged but it didn't seem to make any difference. My next move is to remove all of the plow wiring and see if that helps.

Keep the OPS plugged in,the issue involved there is for 95 and older having a bad OPS and no lift pump operation.

Plugged the ops back on took it to town and I starter to notice that if I slow down to 50-55 and then loor it when I get to 63-64 mph it coughs quick and the keeps on accelerating. I can het this to repeat almost everytime

The turbo lays down around 2400 rpm on these trucks-might be that or it is running out of fuel.

On wide open throttle the LP drops to near 0 fuel pressure and if the filter is dirty it could be some starvation?

there isnt a lot of miles since I changed lift pump (heath diesel) and put a new filter in. This was done last summer, but I dont drive the truck much

---AutoMerged DoublePost---

That also seems to be around the same speed that it will stall at when I am driving normal. Sometimes it will start right back up other times I will have to switch pmds and then it starts

On mine it ended up being a poor connection on the truck side of the pmd harness.

Experiencing similiar symptoms
 

Have 97 6.5 To date have replaced LP, IP, OP, PMD relocation, all new fuel lines to sending unit in tank, fuel filter housing. This thing will run fine just like you explained then out of nowhere starts kicking bucking stall once in a while hard to restart. Have checked grounds and one thing notable as well when it gets below half tank it does it acts up more, or so it seems. Have to get use of a scan tool. Its had EGR code but that's it have not run diagnosis for a while. I am sympathetic and have spent crap load of $$$ Very puzzled. Motor only 114,000 mi. so if anyone out there has ideas let me know.Thanks guys and gals

Try running with the fuel cap loose.

If the vent in the cap is pluged or a gasser cap was installed by mistake it will cause similar symptoms.

I'm having same problems let mW know when u get it figured out